Transmission on channels is exposed to various sources of disturbance. Interference can result. Detection and mitigation of interference is therefore an integral task of modern transmission techniques.
E.g., cable modems in a Hybrid Fiber Coax network operate under the Data Over Cable Service Interface Specification (DOCSIS) protocol. Here, downstream (DS) data is transmitted on a broadcast channel. The DS channel is time-frequency-sliced into a corresponding resource mapping. The resource mapping defines resource elements. Each resource element may have a certain bandwidth and duration. Resource elements correspond to one or more symbols. E.g., the frequency bandwidth of resource elements may correspond to an Orthogonal Frequency Division Multiplex (OFDM) subcarrier.
According to DOCSIS, upstream (US) data is transmitted within well-defined resource elements of the resource mapping. For this, channel synchronization between transmitter and receiver is required. The channel synchronization parameters—such as time-domain offsets and frequency-domain offsets between the transmitter and the receiver—is typically derived from received DS symbols. Time-domain offsets may accumulate to a timing drift.
It has been observed that in various deployment scenarios interference events can degrade the quality of DS data transmission. In particular, such interference events can prevent the accurate determining of the channel synchronization parameters. This, in turn, often prevents US data transmission. Furthermore, after recovery from an interference event, according to reference implementations the time to acquire channel synchronization is significant—such that duration during which US transmission is not possible is additionally prolonged. Further, DS transmission may be interrupted for a significant duration.
An example deployment scenario which is particularly prone to interference events corresponds to the so-called full duplex transmission. Here, a first customer premises equipment (CPE) may communicate on the US channel in a given resource element; while a second CPE may communicate on the DS channel in the given resource element. The communication lines associated with the first and second CPEs may share the same cable bundle. Here, significant crosstalk between the lines associated with the first and second CPEs can cause the interference event. DS communication will suffer from an interference event due to the US communication.